| row/colnames {base} | R Documentation |
Retrieve or set the row or column names of a matrix-like object.
rownames(x, do.NULL = TRUE, prefix = "row") rownames(x) <- value colnames(x, do.NULL = TRUE, prefix = "col") colnames(x) <- value
x |
a matrix-like R object, with at least two dimensions for
colnames. |
do.NULL |
logical. Should this create names if they are
NULL? |
prefix |
for created names. |
value |
a valid value for that component of
dimnames(x). For a matrix or array this is either
NULL or a character vector of non-zero length equal to the
appropriate dimension. |
The extractor functions try to do something sensible for any
matrix-like object x. If the object has dimnames
the first component is used as the row names, and the second component
(if any) is used for the col names. For a data frame, rownames
and colnames are equivalent to row.names and
names respectively, but the latter are preferred (and
can be much faster).
If do.NULL is FALSE, a character vector (of length
NROW(x) or NCOL(x)) is returned in any
case, prepending prefix to simple numbers, if there are no
dimnames or the corresponding component of the dimnames is NULL.
The replacement methods for arrays/matrices coerce vector and factor
values of value to character, but do not dispatch methods for
as.character.
For a data frame, value for rownames should be a
character vector of non-duplicated and non-missing names (this is
enforced), and for colnames a character vector of (preferably)
unique syntactically-valid names. In both cases, value will be
coerced by as.character.
dimnames,
case.names,
variable.names.
m0 <- matrix(NA, 4, 0)
rownames(m0)
m2 <- cbind(1,1:4)
colnames(m2, do.NULL = FALSE)
colnames(m2) <- c("x","Y")
rownames(m2) <- rownames(m2, do.NULL = FALSE, prefix = "Obs.")
m2